so has anyone figured out a way to turn your headlights off. i feel bad every time i go onto the navy base cause i cant turn my headlights off. i heard i can swapout the switch with a newer version... has anyone tried this??

so i put in a 1.5k resister to the light sensor wiring to the BCM. worked like a charm. fyi the 99silverado was a half year and their is no way to turn the headlights off at night. from 2000 on they use the dome over-ride switch to shut them off. it also says this in the chiltons repair manual.

adams99z71 wrote:so i put in a 1.5k resister to the light sensor wiring to the BCM. worked like a charm. fyi the 99silverado was a half year and their is no way to turn the headlights off at night. from 2000 on they use the dome over-ride switch to shut them off. it also says this in the chiltons repair manual.

I would like to do this mod as well would you please clarify what "worked like a charm" means? How does it work now? Which wire did you put the resistor in or does it really matter? THX

You can do the all 4 headlight mod real easy to on that 1999 truck also by grounding the low beams negative wire on both low beam lights to the body with an extra wire cutting the original wire completely. When the high beams are on the truck cancels the ground to the low beams and they go out, and with this mod they have a ground and will stay on instead of going out.__________________

I have read several posts asking for information on how to disable the twilight (auto on) feature on the headlights of 99 FSCs.I wanted to do this myself so I searched and found several methods of doing it.This is the easiest. You don't have to take the dash apart or cut any wires. Just a simple in line resistor.Here it goes:

First locate the Body Control Module (BCM) which is under the dash, below the steering column. Laying on the floor, this should be visible without removing any dash panels. You should find a purple connector (C3). Unplug it.

Locate the white and gray wires (A4 and A6). I don't remember if white is A4 and gray is A6 or vice versa. It doesn't matter anyway. BTW - there are two gray wires in the connector. The one you want is the one farthest away from the white wire.

Tap the gray wire from the plug (C3) to one end of the resistor and the white wire to the other end. You don't need to cut the wires. Make sure you tape up all wires to prevent a short. You should now have a gray wire coming from C3 tapped to one lead of the resistor and the white wire from C3 tapped to the other resistor lead *. Plug C3 back into the BCM. Start the truck and make sure the lights are off. Throw a dark towel or something over the light sensor on the dash and verify the lights stay off. Try your light switch that has probably never been used and that's it! Takes about 5 minutes.

*You can add a switch here if you want. Just connect one end of the resistor to one of the wires in the connector (doesn't matter which one) and the other end of the resistor to one side of the switch. Then connect a wire from the other side of the switch to the other wire in the connector. This will allow you to turn Twilight Mode on and off, however there will be some delay because the bcm only checks the sensor every 30 seconds

adams99z71 wrote:so has anyone figured out a way to turn your headlights off. i feel bad every time i go onto the navy base cause i cant turn my headlights off. i heard i can swapout the switch with a newer version... has anyone tried this??

ive tried that before and it didnt work for me. maybe i dont have the right Auto Repair Manual for that. try to find it.